The present invention relates to high rising projectable sprinklers with a rotating nozzle or nozzles which are automatically projected or advanced to a position above the surrounding ground level when water is supplied under pressure to the sprinkler.
The advantages of a projectable sprinkler include avoidance in a lawn, farm or orchard of a permanently raised fixture which causes accidents, which is unsightly and around which the grass must be edged or clipped by hand, and avoidance of damage to a sprinkler system by children playing with a permanent, elevated standpipe, or by accidently hitting such a standpipe with a lawn mower, tractor or car.
To realize such advantages, many forms of projectable sprinklers have been proposed, both commercially and in the patent literature. U.S. Pat. Nos. 3,104,822; 2,611,644; 2,013,849 and my U.S. Pat. No. 3,709,435 disclose various types of projectable sprinklers.
One difficulty encountered in making a commercially successful projectable sprinkler has been the complexity and number of parts required. Most sprinklers are costly to manufacture, difficult to assemble, repair, and service, and are unreliable in operation. In addition, some prior art sprinklers have suffered from the inability to seal well, thus causing an unnecessarily large drop in pressure so that fewer projectable sprinklers than permanently raised sprinklers could be used on a supply line of a given hydraulic capacity.
An additional problem encountered in some prior art projectable lawn sprinklers is that to prevent the standpipe projected from the ground from rocking it was necessary to have the relatively movable parts fit one another quite closely and to have lengthy bearing surfaces, i.e., lands. On the other hand, when the parts fit closely, substantial friction developed and foreign matter tended to stick between the parts. This sometimes jammed the standpipe and at other times scored the parts so as to permit leakage to develop. Furthermore, the use of long lands required additional effort to raise the standpipe and made it more vulnerable to jamming.
Further disadvantages of some prior art projectable lawn sprinklers were that they did not tend to assume and maintain the same predetermined substantially vertical position each time they were erected, that they did not erect to great heights because clearances and friction were multiplied when the movement of the standpipe from retracted to extended position became appreciable, and that grass would frequently grow over the top of the projectable lawn sprinkler and prevent the sprinkler from rising.
Furthermore, some prior art lawn sprinklers could not be advanced or projected above the ground when the housing of the sprinkler was filled with water, and thus the area wetted by the sprinkler was undesirably small.